647 research outputs found
Short-time critical dynamics and universality on a two-dimensional Triangular Lattice
Critical scaling and universality in short-time dynamics for spin models on a
two-dimensional triangular lattice are investigated by using Monte Carlo
simulation. Emphasis is placed on the dynamic evolution from fully ordered
initialstates to show that universal scaling exists already in the short-time
regime in form of power-law behavior of the magnetization and Binder cumulant.
The results measured for the dynamic and static critical exponents, ,
, and , confirm explicitly that the Potts models on the
triangular lattice and square lattice belong to the same universality class.
Our critical scaling analysis strongly suggests that the simulation for the
dynamic relaxation can be used to determine numerically the universality.Comment: LaTex, 11 pages and 10 figures, to be published in Physica
Organizacao do banco de sementes botanicas do banco ativo de germoplasma de batata-doce, para conservacao do "pool genico" a longo prazo.
bitstream/item/109233/1/Organizacao-do-banco-de-sementes-botancias.pd
Microscopic Non-Universality versus Macroscopic Universality in Algorithms for Critical Dynamics
We study relaxation processes in spin systems near criticality after a quench
from a high-temperature initial state. Special attention is paid to the stage
where universal behavior, with increasing order parameter emerges from an early
non-universal period. We compare various algorithms, lattice types, and
updating schemes and find in each case the same universal behavior at
macroscopic times, despite of surprising differences during the early
non-universal stages.Comment: 9 pages, 3 figures, RevTeX, submitted to Phys. Rev. Let
Escaping Plato's Cave using Adversarial Training: 3D Shape From Unstructured 2D Image Collections
We introduce PLATONICGAN to discover the 3D structure of an object class from an unstructured collection of 2D
images, i. e., neither any relation between the images is available nor additional information about the images is known.
The key idea is to train a deep neural network to generate
3D shapes which rendered to images are indistinguishable
from ground truth images (for a discriminator) under various camera models (i. e., rendering layers) and camera
poses. Discriminating 2D images instead of 3D shapes allows tapping into unstructured 2D photo collections instead
of relying on curated (e.g., aligned, annotated, etc.) 3D data
sets. To establish constraints between 2D image observation
and their 3D interpretation, we suggest a family of rendering
layers that are effectively differentiable. This family includes
visual hull, absorption-only (akin to x-ray), and emissionabsorption. We can successfully reconstruct 3D shapes from
unstructured 2D images and extensively evaluate PLATONICGAN on a range of synthetic and real data sets achieving
consistent improvements over baseline methods. We can also
show that our method with additional 3D supervision further
improves result quality and even surpasses the performance
of 3D supervised methods
Total Denoising: Unsupervised Learning of 3D Point Cloud Cleaning
We show that denoising of 3D point clouds can be learned unsupervised, directly from noisy 3D point cloud data only. This is achieved by extending recent ideas from learning of unsupervised image denoisers to unstructured 3D point clouds. Unsupervised image denoisers operate under the assumption that a noisy pixel observation is a random realization of a distribution around a clean pixel value, which allows appropriate learning on this distribution to eventually converge to the correct value. Regrettably, this assumption is not valid for unstructured points: 3D point clouds are subject to total noise, i.e. deviations in all coordinates, with no reliable pixel grid. Thus, an observation can be the realization of an entire manifold of clean 3D points, which makes the quality of a naive extension of unsupervised image denoisers to 3D point clouds unfortunately only little better than mean filtering. To overcome this, and to enable effective and unsupervised 3D point cloud denoising, we introduce a spatial prior term, that steers converges to the unique closest out of the many possible modes on the manifold. Our results demonstrate unsupervised denoising performance similar to that of supervised learning with clean data when given enough training examples - whereby we do not need any pairs of noisy and clean training data
First lattice evidence for a non-trivial renormalization of the Higgs condensate
General arguments related to ``triviality'' predict that, in the broken phase
of theory, the condensate re-scales by a factor
$Z_{\phi}$ different from the conventional wavefunction-renormalization factor,
$Z_{prop}$. Using a lattice simulation in the Ising limit we measure
$Z_{\phi}=m^2 \chi$ from the physical mass and susceptibility and $Z_{prop}$
from the residue of the shifted-field propagator. We find that the two $Z$'s
differ, with the difference increasing rapidly as the continuum limit is
approached. Since $Z_{\phi}$ affects the relation of to the Fermi
constant it can sizeably affect the present bounds on the Higgs mass.Comment: 10 pages, 3 figures, 1 table, Latex2
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